Hey Rick. Check out bismic post about buying a used 6.0, also read the tech folder there is a lot of good info in there for you to look for. The main things I would look for in a 6.0 is as folows.
1. White resuidue around the degas bottle (could mean bad egr cooler/blown HG.)
2. Be sure there isn't an am intake on it (they are known to cause problems)
3. Use only oem filters (will-fit ones are bad)
4. It would be nice to know the maintance history (ie..get an oassis report)
5. see if head studs have been installed (would be nice if they are, but not nessary)
6. check all fulid levals
7. I wouldn't buy one that has had, or has, any off the self tunner ie..Bully dog, banks, edge. The only two I would be ok with having had is SCT, or Spartan. either one with custom tunes.
That is a start there will be others with more info that I haven't thought about yet. As far as mod you should do yourself. I would install a coolant filter first thing. Also consider getting gauges to include at least ECT, EOT, and fuel pressure. If you go the tuned route I would also get EGT's, Boost (depending on the year), and Trans Temp.
The 05 engines did recieve some updates, but I would say that is not necessarly a bad thing. If you made up your mind about purchasing an Excursion I would focus on purchasing an 05 model in hopes you may have a little warrenty left (only months at this point) and the option to purchase a Ford ESP plan.
If you kept that Chevy 6.5 engine running this long I would think you wouldn't have a problem with the Excursion. We had a 97 Chevy 6.5 turbo diesel and they had there share of problems.
Yeah.. The just about ALL 94/95 models needed a replacement injection pump. I of course didn't replace mine until the warranty expired.....
I did all the work myself too. The OBD-I 6.5L diesel is pretty easy to work on.......(and luckily, GM reimbursed me for all the parts after the fact!)
I have no doubt I can work on a power Stroke engine too....I just don't want to get a model that might have been in a "lemon" year.....
I am hoping that there really was no particular year with big problems....
Generally speaking every year of the 6.0 life span recieved some level of improvements. The largest number of improvements came on the 04 model year and the smallest qty was with the 07 model year which doesn't apply to the Excursion.
If you do purchase an Excursion with a 6.0 then you will need to camp out here and read all the sticky's as there is alot go good info. If you do run into problems this is the place to be with alot of good help.
If you haven't driven a 6.0 psd your in for a treat. The power of the 6.0 will make that old 6.5 feel like a turd.